LONG-TERM OBJECTI VES: (1) Develop a standardized procedure involving the use of immunological tolerance for producing highly-specific monoclonal antibodies (mAbs) reactive with unique epitopes of Bacillus anthracis (the ethological agent of anthrax) but not with epitopes shared with closely related species in the highly monomorphic B. cereus family, of which B. anthracis is a member. (2) Use the specific mAbs to produce immunochromatographic test strips to be used by (a) Hazmat first responders (e.g., fire fighters, law enforcement) or state and federal government personnel for rapid on-site detection of anthrax in environmental samples, and (b) public health laboratory and hospital personnel for rapid detection and confirmation of anthrax from primary bacterial culture of clinical or environmental samples. (3) Utilize tolerance procedures for developing highly-specific mAbs to other human or animal pathogens. SPECIFIC AlMS: (1) Test existing and novel tolerization techniques for the abiity to eliminate antibody responses to antigens shared by B. anthracis and closely related species while preserving B. anthracis specific responses after multiple post-tolerization immunizations with B. anthracis antigens. (2) Use spleen cells from specifically tolerized-immunized mice to produce hybridomas. (3) Identify hybridomas that secrete high-affinity B. anthracis-specific lgG mAbs and maintain this function after cryopreservation. (4) Store frozen aliquots of these hybridomas for use in Phase II studies to develop a mAb-based device for rapid detection of B. anthracis. HEALTH RELATEDNESS: The deadly nature of inhalational anthrax, hardiness of anthrax spores and relative ease of weaponization make B. anthracis one of the most likely biothreat agents for use by state-sponsored or individual bioterrorists, as underscored by events occurring after the 11 September 2001 terrorist attacks on the U.S. Due to the extreme monomorphism of the B. cereus family, efforts to produce a mAb reactive with B. anthracis but none of its close relatives have failed. Absolute specificity of anthrax diagnostic mAbs is essential because (1) cross-reactive bacilli are common in environmental samples, and (2) bioterroristic hoaxes have already been carried out, using spore-forming bacteria closely related to B. anthracis (e.g., B. thuringensis, commonly available as an insecticide) to simulate an anthrax attack.